its’ not practical to give everyone write access to the google.com root zone.
Someone will fuck up accidentally, so production zones are usually gated somehow, sometimes with humans instead of pure automata.
Why not ?
Giving write access does not mean giving unrestricted write access
Also, another way (which I built in a previous compagny) is to create a simple certificate provider (API or whatever), integrated with whatever internal authentication scheme you are using, and are able to sign csr for you. A LE proxy, as you might call it